Process for the production of water-resistant paper or nonwovens containing water soluble polyvinyl alcohol

ABSTRACT

A PROCESS FOR THE PRODUCTION OF PAPER OR NONWOVENS COMPRISING IMPREGNATING AT 40*C. OR BELOW PAPER OR NONWOVENS CONTAINING A WATER-SOLUBLE POLYVINYL ALCOHOL WHICH DISSOLVES IN WATER AT 95*C. OR BELOW WITH AN AQUEOUS MINERAL ACID SOLUTION OF A-TITANIC ACID WHICH HAS A TITANIUM CONCENTRATION OF AT LEAT 0.2% BY WEIGHT AND WHICH IS PREPARED AT 40*C. OR BELOW, THEN RINSING AND DRYING.

July 25, 1972 TADAQ |K A ETAL 3,679,544

PROCESS FOR THE PRODUCTION OF WATER-RESISTANT PAPER 0R NONWOVENS CONTAINING WATER SOLUBLE POLYVINYL ALCOHOL Filed Aug. 11, 1969 MINERAL ACID CONCENTRATIOMNORMAL CONCENTRATION N) 5 TITANIUM CONCENTRATION I United States Patent Office 3,679,544 Patented July 25, 1972 US. Cl. 162-457 R 7 Claims ABSTRACT OF THE DISCLOSURE A process for the production of paper or nonwovens comprising impregnating at 40 C. or below paper or nonwovens containing a water-soluble polyvinyl alcohol which dissolves in water at 95 C. or below with an aqueous mineral acid solution of a-titanic acid which has a titanium concentration of at least 0.2% by weight and which is prepared at 40 C. or below, then rinsing and drying.

The present invention relates to a process for the production of water-resistant paper or nonwovens and more particularly to the production of paper or non-wovens which are water resistant, especially resistant to warm and hot Water and of low moisture absorption and good fastness to washing and have their prime fibers adhered to one another with a binder such as water-soluble polyvinyl alcohol fibers or resin having a dissolving temperature of 95 C. or below.

Paper or nonwovens composed in whole or in part of polyvinyl alcohol (hereinafter called PVA containing paper or nonwovens) are treated at temperatures of 40 C. or below with an aqueous mineral acid solution of a-titanic acid having at least 0.2% titanium as metal titanium at 40 C. or below, rinsed and then dried.

The main defect of PVA containing paper or nonwovens is that they are not resistant to hot water. If they are immersed in boiling water, polyvinyl alcohol is dissolved, and the main fibers are dispersed.

Heretofore in order to improve water resistance of PVA containing paper or nonwovens, acetalization by a monoaldehyde, such as formaldehyde, benzaldehyde, etc. and cross-linking with a dialdehyde, such as glyoxal, phthalaldehyde, etc. have been carried out.

However since PVA containing paper or nonwovens, particularly the ones which use PVA type fibers or resin as a binder dissolve in hot water at 50 to 90 C., which is the dissolving temperature of the binder, the reaction temperatures in the acetalization and cross-linking reactions cannot be raised, and sufiicient Water-resistant effect is unobtainable. These processes have the following unavoidable defects: At the temperatures and reaction time for acetalization and crosslinking reaction, paper or nonwovens are swelled and contracted; the steps of operations are complicated; and such faults as coloring, variations in feel and decrease in strength are seen.

US. Pat. 2,518,193 discloses the PVA in film, fiber or granular form is titanated using at least 1% of titanium by weight with chlorine-free, water-soluble tetravalent titanium salts, e.g. titanyl sulfate (TiOSO -2H O), titanium sulfate, titanium oxalate, titanium hydroxyacetate, glyceryl titanate, etc. The film produced from one type of titanium containing PVA plastic is insoluble in hot water, has improved wet and dry strengths, and exhibits greater dimensional stability and higher transparency to visible light. The titanium-containing PVA having such properties is obtained in the following reaction:

Further, chlorine-containing compounds as titanating agents are not useful because films treated with such compounds become degraded and disintegrate after treatment.

US. Pat. 2,549,940 discloses that titanated polyvinyl acetate film and adhesives are obtained by the treatment of an aqueous emulsion of partially, up-to-50% hydrolyzed polyvinyl acetate, polyvinyl ester or polyvinyl acetals with titanium compounds, e.g. titanyl sulfate, titanium lactate, freshly-precipitated titanium hydroxide, ortho-(meta-)titanic acids, pertitanic acid, titanium acetate, titanium oxylate, titanium glycolate, hydrous uncalcined titanium dioxide, etc. The titanated films so obtained are transparent and tough when dried, have much moisture absorption properties, and retain their strength and elasticity after prolonged exposure in water at room temperature. The adhesives are strong in adhesive power in boiling water and have particularly effective applications in the sizing and impregnation of paper and textile fibers.

According to the present invention, it has been found that the water resistance, especially resistance to hot water, low moisture absorption and good fastness to washing of water-soluble PVA containing paper or nonwovens having water-dissolving temperatures of C. or below can be remarkably improved by treating the paper or nonwovens below 40 C. with a solution which has been prepared by the addition below 40 C. of titanium tetrachloride to water or a solution of mineral acid of a precipitate which has been prepared by adding titanium tetrachloride to water and then adding ammonia. Further, it has been discovered that the treating solution in the present invention can be stabilized by maintaining it to specified titanium and mineral acid concentrations or by making a mineral acid solution containing 40% or above of alcohol, and that by use of such stabilized treating solution, paper or nonwovens of consistent high degrees of water resistance and good fastness to washing are obtainable.

The present invention provides in one embodiment a process for the production of water-resistant PVA containing paper or nonwovens comprising impregnating water-soluble PVA containing paper or non-wovens having water-dissolving temperatures of 95 C. or below with a solution which has been prepared by the addition of titanium tetrachloride to water at 40 C. or below, a solution made by dissolving in mineral acid a precipitate which has been prepared by the addition of titanium tetrachloride to water and the subsequent addition of ammonia and drying the resultant product.

Further, the invention provides the manufacture of water-resistant PVA containing paper or nonwovens comprising impregnating water-soluble PVA containing paper or nonwovens having water-dissolving temperatures of 95 C. or below with a stabilized treating solution having specified titanium and mineral acid concentrations in the stabilized region of the solution stabilizations curve shown in the relation between titanium and mineral acid concentrations in a solution which has been prepared by adding titanium tetrachloride to water at 40 C. or below, and a solution made by dissolving in mineral acid a precipitate which has been prepared by adding titanium tetrachloride to water, adding ammonia and then drying the resultant product.

The invention further provides the manufacture of water-resistant PVA containing paper or nonwovens by dipping water-soluble PVA paper or nonwovens having water-dissolving temperatures of 95 C. or below in the stabilized treating solution at temperatures of 40 C. or below, such solution containing a solution prepared by adding titanium tetrachloride to water, a solution made by dissolving in mineral acid the precipitate from the addition of titanium tetrachloride to water and the subsequent addition of ammonia with more than 40% of alcohol.

The treating solutions to be used in treating PVA containing paper or nonwovens include a solution prepared .by adding titanium tetrachloride to water at 40 C. or

below, and a mineral acid solution from a precipitate formed by adding titanium tetrachloride to water and subsequently ammonia, the methods of preparation thereof and their components being critical features of the present invention.

The solution should be prepared by adding titanium tetrachloride to water at 40 C. or below If the temperature is higher than that, a white precipitate is generated and it is impossible to impart to PVA type paper or nonwovens favorable water-resistance; therefore a higher temperature than 40 C..should be avoided. Ultimately an aqueous solution with a titanium concentration of 15%, and a hydrochloric acid concentration of 35-40% (usually 40%) (generated by the hydrolysis of titanium tetrachloride) can be caused.

When the solution is actually used, it is diluted in water so that a titanium concentration is 0.2 to 5.0% by weight on the basis of the weight of solution, preferably 0.5 to 2.0% by weight. At a titanium concentration below 0.2% by weight, the desired water-resistance cannot be imparted to paper or nonwovens. With a titanium of more than by the hydrochloric acid concentration becomes approximately 14% or above resulting in the contraction, degradation, or disintegration of paper or nonwovens. This solution is of chlorine-containing agents containing a-titanic and hydrochloric acids generated by the hydrolysis of titanium tetrachloride. In the light of the disclosure in U.S. Pat. 2,518,193 that chlorine-containing titanium compounds are non-usable, it is surprising that chlorineeontaining titanium solutions are usable and that when the solution in the present invention having a titanium concentration of 0.2 to 5.0% by weight and a hydrochloric acid concentration of 14% or below is employed, paper or nonwovens exhibit highly improved water resistance and fastness to washing instead of becoming degraded and disintegrating after treatment. The chemical process is not clear but it seems that the ring formation by titanium as described in US. Pat. 2,518,193 will proceed to partial cross-linking. The mineral acid solution from the precipitate formed by adding titanium tetrachloride to water followed by the addition of ammonia is prepared in the following manner:

Titanium tetrachloride isadded to water and ammonia is then added; the generated precipitate is filtered off and dissolved in mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. The precipitate formed by the addition of ammonia is considered to be mostly a-titanic acid. This solution can be made into an aqueous solution having a titanium concentration of about 15% and a mineral acid concentration of about 35 to 40%. The amounts of water and the concentration and amounts of ammonia to be used are not so critical and amounts of water sufiicient to dissolve titanium tetrachloride and amounts and concentration of ammonia suflicicnt to precipitate titanium tetrachloride will suflice. Actually, before it is used, the hydrochloric acid solution is diluted like the solution prepared by the addition of titanium tetrachloride to water. In using a sulfuric acid solution, it is diluted up to a titanium concentration of 0.2 to 5.0% by weight, preferably 0.5 to 2.0% by weight and sulfuric acid concentration of about 0.7% or above by weight, preferably 1.8 to 7.2% by weight. When using a nitric acid solution, a nitric acid concentration of 0.9 to 23.0% by weight is used. The precipitate is considered to consist wholly or mostly of a-titanic acid. Thus, for instance, commercial a-titanic acid can be used in like manner as a mineral acid solution. However, for rendering PVA containing paper or nonwovens water resistant, a mineral acid solution prepared through precipitation tends to exhibit more favorable results, at least uniform results.

The treating solutions are diluted when used. For instance, if they are diluted to a titanium concentration of 5% by weight or below and allowed to stand, a white precipitate is caused, and the concentration of a-titanic acid dissolved in the solution decreases. The more the solution is diluted with water, the more readily the white precipitate is generated. When the white precipitate is generated in the diluted solution, PVA containing paper or nonwovens treated with this diluted solution become less water-resistant and more soluble in boiling water and lose water-resistance and insolubility in hot water.

It has been found that the undesirable white precipitate can be very effectively prevented by incorporating alcohol. That is, alcohol is usable as a stabilizing agent for the solutions.

Alcohols as a stabilizer include lower monohydric alcohols such as methyl alcohol, ethyl alcohol, normal or isopropyl alcohol, normal, iso or neo butyl alcohol, amyl alcohol, isoamyl alcohol, etc, lower dihydric alcohols such as ethylene glycol, 1-2 propylene-diol, etc., lower t-rihydric alcohols such as glyccrine, lower tetrahydric alcohols such as pentaerythritol, etc., alcohols such as watersoluble polyvinyl alcohol, and mixtures of more than two of the above. The addition of the alcohol is preferably done to the treating solutions except polyvinyl alcohol.

The addition may be done to the diluted solutions of the treating solutions. The amounts of alcohols except polyvinyl alcohol are determined so that 40% or above by weight, preferably 40% to by weight is incorporated in the treating solutions, and they become 1 to 10% by weight, preferably 2 to 7% by weight when the alcoholcontaining treating solutions are diluted to a titanium concentration of 5% by weight or below. Outside the range of the amounts of use, there are some cases when stabilimtion is possible. In using polyvinyl alcohol as a stabilizer in the treating solutions, an aqueous PVA solution which has been separately prepared by diluting PVA with water to 3 by weight or below, preferably 0.01 to 2% by weight is added little by little to the aqueous treating solutions having a titanium concentration of 5% by weight or below, preferably 0.5 to 3.0% by weight, and it is thoroughly agitated. Since polyvinyl alcohol is solid, it is necessary to dissolve it in an aqueous mineral acid solution of atitanic acid. When solid polyvinyl alcohol is incorporated in a mineral acid solution of a-titanic acid and heated, a chemical change is caused because of the unstability to heat of a-titanic acid in the solution or a-titanic acid reacts with polyvinyl alcohol forming a water-insoluble substance, resulting in the insolubility of polyvinyl alcohol. Therefore, polyvinyl alcohol is dissolved in water beforehand and the resultant PVA solution is added to an aqueous mineral acid solution of a-titanic acid. Even in that case, if an aqueous PVA solution of a high concentration is added to a diluted a-titanic acid solution, the aqueous PVA solution instantly causes gelling over the entire solution and a substance insoluble in water is formed. Accordingly, it is desired that an aqueous PVA solution of 3% by weight or below, particularly 0.01 to 2% is added. On the other hand, with the use of the aqueous solution of polyvinyl alcohol the concentration of which has been lowered to 0.01%, gelling occurs if the titanium concentration is 5% by weight or above. The titanium concentration, therefore, should be 5% by weight or below. Care must be taken so that the PVA solution should be added little by little to the titanium solution while the titanium solution is being agitated in the mixer. When the PVA solution, even if diluted, is added to a mineral acid solu tion of a-titanic acid at one time, a gel from a-titanic acid in the solution and PVA occurs and sticks to the walls of a vessel or the impellers of an agitator and is diflicult to remove.

As polyvinyl alcohol, polyvinyl alcohol obtained by the full hydrolysis of polyvinyl acetate, a water-soluble, partly-hydrolyzed PVA, PVA derivatives, partly-hydrolyzed polyvinyl esters such as polyvinyl propionate, polyvinyl butyrate, polyvinyl valerate, and polyvinyl formate and polyvinyl acetals obtained by partial condensation of PVA with an aldehyde such as formaldehyde, acetaldehyde, and N-butaldehyde, which derivatives contain the whole or part of PVA structure and are water-soluble in the stated amounts may be used. The degree of polymerization of PVA is that of commercial PVA, preferably 500 to 2,000. Such treating solution shows a good stability when an alcohol and a mineral acid such as hydrochloric acid and sulfuric acid are contained in said solution.

Further it has been found that the undesirable white precipitate can be prevented by adjusting the concentrations of titanium in the treating solutions and of mineral acid above the solution stabilization curve drawn in relation to titanium concentration versus mineral acid concentration shown in the accompanying drawing. The curve in the figure show the lower limit of mineral acid concentration in the treating solutions stable more than 4 days at normal temperatures required for the operations. (That no occurrence of white precipitate after the solution has been allowed to stand for 4 days is regarded as stable.) A stabilized solution is obtained by adjusting mineral acid to a concentration above the range as shown in the curve. However, the titanium concentration in the treating solution increases, that of the mineral acid increases, and degradation of PVA containing paper or non-wovens is caused. Therefore, the concentration of mineral acid cannot be increased infinitely. The curve in the diagram is one that causes PVA containing paper or nonwovens to exhibit slightly low strength.

vWhen PVA containing paper or nonwovens are treated with such stabilized treating solutions, paper or nonwovens having at least uniform water-resistance are obtainable in easy operation. Further the alcohol-containing stabilized treating solutions are particularly effective for easily obtaining paper or nonwovens having high degrees of water resistance, when the treatment is found to be very difiicult because of the low strength of paper in treating only with an aqueous solution of u-titanic acid paper or nonwovens containing PVA the water-dissolving temperature of which is 95 C. or below, particularly paper having a small basic weight, e.g. l g./m. or below or weak paper the waterdissolving temperature of which is 85 C. or below or when the treatment for insolubilizing PVA containing paper or nonwovens only with an aqueous solution of a-titanic acid is found to be very difficult because of a high shrinkage of paper in water, because paper or nonwovens exhibit very low decrease in strength in the watercontaining alcohol.

PVA containing paper or nonwovens are imparted high degrees of water resistance, particularly resistance to boiling water, low moisture absorption properties and high fastness to washing by impregnating them with the treating solutions, alcohol-containing, stabilized treating solutions, or treating solutions stabilized by a specified concentration for 2 min. and subsequently rinsing and drying according to the present invention.

PVA containing paper or nonwovens in the invention include the ones that use, as their prime fibers, polyvinyl alcohols, nylons, polypropylenes, polyesters, rayon, all the other synthetic fibers, wood pulp, bast fibers such as abaca, cotton linters, etc. solely or by mixing two or more kinds of the above. The paper or nonwovens containing PVA having a water-dissolving temperature of 95 C., specifically 50 to 95 C. are obtained by the addition or impregnation of a PVA type binder of preferably 5 to 30% by weight, to bond these main fibers or to improve the strength of the paper or nonwovens composed of these main fibers and by the subsequent drying of the product. Some PVA containing paper or non-wovens containing PVA of a water-dissolving temperature of 95 C. or below have no binder added.

PVA type binders include PVA fibrous and resinous binders. The PVA fibrous binders are used for bonding the prime fibers or increasing the strength of pulp, paper or nonwovens. The PVA to be used has a degree of polymerization of 500 to 2,000, preferably 700 to 1,800 and a degree of saponification of to 99.9%, preferably 87 to 98%. The PVA fibrous binder is prepared by drawing PVA to 2.5 to 4 times in the wet state after spinning and then drying it. The fibers are cut to 2 to 70 mm. The temperature of water-dissolving is 50 to 90 C. and the fiber size is 0.8 to 6.0 denier. Conventional PVA fibrous binders having a dissolving temperature of 50 to 90 C. in water and which are conventionally used as PVA fibrous binders can be used. The PVA resinous binder is used for bonding the prime fibers or increasing the strength of pulp-paper or nonwovens. The PVA of the resnous binder has a degree of polymerization of 500 to 2,000, preferably 700 and 1,800, and a degree of polyvinyl acetate saponification of 85 to 99.9% preferably 87 to 98%. The resinous binder is usually in the powder state. It is usually added in the form of powder and sometimes made to impregnate the manufactured paper or non-wovens. In manufacturing paper, conventional paper manufacturing machines such as Fourdrinier, cylinder machines, etc. can be used, and beaters, refiners, etc. are suitable for incorporating a PVA binder. In incorporating it into nonwovens, conventional methods are used. In either the worsted system or the random Wcbber methods for the manufacture of nonwovens, a PVA binder very often is added at the feeder, but nonwovens may be impregnated with the binder after the formation of nonwoven sheet. In treating paper which has been made from cellulosic fibers bonded with a PVA type binder with the treating solution in the present invention, it is desired to impregnate the paper previously with an aqueous solution of 0.5 to 3% by weight of PVA type resin, for instance known vinyl alcohol polymer and to dry it. In order that PVA type resin film may occur on the surface of each fiber forming the paper, but not on the surface of the paper, it is desired to dry the paper with hot air or with radiant heat while holding the paper in the air, on the net or cloth instead of pasting it up on a plane. If PVA type resin film is formed on the surface of paper, the paper becomes a laminate with the film and loses its function as paper.

In the impregnation, the concentration of PVA resin solution is required to be 0.5 to 3% by weight, and with less than 0.5%, paper having high wet strength in the invention is unobtainable. On the other hand, with more than 3% the film of PVA resin tends to occur on the surface of the paper, and the paper becomes hard.

The paper impregnated and dried under such conditions is treated with an aqueous mineral acid solution of tX-titaHiC acid, and the titanium concentration in the aqueous mineral acid solution of a-titanic acid is required to be 0.2 to 5%. With less than 0.2%, paper of high wet strength and high degrees of water resistance aimed at in the present invention cannot be produced. With more than 5%, the degradation of PVA-containing paper or nonwovens takes place. The treating temperature may be normal and the treating length of time about 30 min. The paper obtained by the above methods excels in low moisture absorption and water resistance.

The dissolving temperature in water of PVA are determined in the following manner.

As to PVA fibrous binders, 100 denier filament fibers are sampled, arranged in parallel into a bundle, and one end of the bundle is secured on a rule. At a distance of 5 cm. from the end, a load of 2 mg. per denier is placed, and the specimen is put into a test tube containing water. The test tube is heated so that the water temperature in the test tube can rise 1 C. per minute from 20 C. The breakage of the fibers in the test tube is observed and the temperature at which the fibers are broken is measured. This is a temperature at which PVA is dissolved in water.

As to PVA resinous binder, about g. of powdery PVA is placed in a beaker having a capacity of 2 liters containing 1,000 milliliters of water. While the specimen is being agitated with a glass stirrer at 100 revolutions per min., it is heated so that from 20 C. the water temperature in the test tube can rise 1 C. per min. The temperature at which the PVA in the test tube in completely dissolved is a dissolving temperature of PVA powder in water.

The invention will be described below by embodiments but it is to be understood that the invention is not limited thereto. In the embodiments, parts are based on weight unless otherwise specified.

EXAMPLE 1 In titanating PVA paper, raw paper was prepared as follows:

80 parts 1.5 denier PVA fibers with 3 mm. cut lengths as prime fibers 30 percent of which were formalized and 20 parts of 1.5 denier PVA fibers with 3 mm. cut lengths, having a dissolving temperature in water of 80 C. were used to make paper with a cylinder machine. The basic weight of paper was 60 g./m.. The paper was dipped for one minute in an aqueous solution of u-titanic acid having a titanium concentration of 1.0% and a hydrochloric acid concentration of 2.7%, rinsed 10 minutes in running water, and dried. The titanic acid treating solution was prepared by diluting the a-titanic acid solution having a titanium concentration of and a hydrochloric acid concentration of 40% with water at C.

, The titanated PVC paper was steeped in hot water at 100 C. for 10 min., then taken out, and measured with a Schopper tensile machine in the wet state for its longitudinal tensile strength. The test result was 2.8 km. in breaking length and that of the processed paper dipped for 24 hours in water at 20 C. was 4.2 km. in the wet state. When the unprocessed paper was placed in hot water at 100 C. the PVA fibrous binder was dissolved and decomposed completely into single fibers and the longitudinal breaking length in the wet state after its immersion in water at 20 C. for 24 hrs. was 2.1 km. It has been dis covered by this experiment that the water resistance and insolubility in hot water of PVA paper can be improved by titanation.

EXAMPLE 2 1.5 denier rayon produced by the conventional viscose process was cut into the cut length of 5 mm. 70 parts the fibers as prime fibers and 30 parts 1.5 denier polyvinyl fiber with the cut length of 3 mm. having a dissolving temperature in water of 80 C. as a binder were used to make paper with a cylinder machine, and the resulting paper was titanated. The basic weight of this paper was 40 g./m.'. The treating solution of a-titanic acid was prepared by the methods in Example 1, used for the treatment of ray under the conditions of 0.5 titanium concentration, 1.3% hydrochloric acid concentration, an immersion length of time of one minute.

- The titanated paper was dipped in hot water at 100 C. for 10 minutes, and the longitudinal breaking length in the wet state was 0.3 km. The breaking strength of the rayon paper after 24 hours. immersion in water at 20 C. was 0.9 km. However the untitanated rayon paper instantly lost its configuration and very soon disintegrated into single fibers on immersion in hot water. The longitudinal breaking length after 24 hrs. immersion of this untitanated paper in water at 20 C. was 0.05 km. As stated above titanation is very elfective is elevating water-resistance of PVA rayon paper.

8 EXAMPLE 3 parts 3.0-denier PVA fibers with a cut length of 50 mm. 30% of which was formalized as prime fibers and 20 parts 2.0-denier PVA fibers with a cut length of 40 mm. having a dissolving temperature in water of 60 C. as a binder were used for the manufacture of nonwovens. In the preparation of nonwovens, the raw material prime fibers and the binding fibers were dipped in water after they passed through the feed card in the worsted system and then dried with hot air. The basic weight was 25 g./ mi. This nonwoven cloth was dipped one minute in an aqueous solution of tX-titaniC acid having a titanium concentration of 1.0% and a hydrochloric acid concentration of 2.7%, rinsed, and dried. This titanated nonwoven fabric was dipped in hot water at 100 C. for 10 minutes. The longitudinal breaking length in the wet state was 1.2 km. The unprocessed nonwoven disintegrated in hot water.

[EXAMPLE 4 NL.B.KP pulp (needle leaved tree-bleached kraft pulp) was heated with a beater into Canadian freenessof 500 milliliters. 80 parts the NL.B.KP pulp and 20 parts 1.5 denier PVA fibrous binder with a cut length of 3 mm. having a dissolving temperature in water of 80 C. were employed to manufacture paper with a cylinder machine. The resultant paper was dipped one minute in an aqueous a-titanic acid solution having a titanium concentration of 0.5% and a hydrochloric acid concentration of 1.3%, rinsed, and dried. The basic weight of the paper was 60 g./m. After one hours boiling in hot water at 100 C., the paper not only still retained the configuration of paper, but was tough. On the other hand, when the untitanated paper was immersed in hot water at 100 C., it did not disintegrate completely into single fibers but swelled completely and, without any appreciable strength, partly delaminated when held up with pincers.

EXAMPLE 5 in an aqueous a-titanic acid solution having 1.0% titanium concentration and 2.7% hydrochloric acid concentration for one min., rinsed and dried. The titanated paper was immersed in hot water at 100 C. for 10 min., and the breaking strength in the wet state was 2.1 km., but without titanation, the paper swelled in hot water at 100 C. losing strength. The paper was damaged to a considerable extent but not to disintegration into individual fibers.

EXAMPLE 5 A web of only PVA fibers, 3.0-denier, 50 mm. long, 30% of which was formalized was formed with a card,

dipped in an aqueous 3% PVA solution, squeezed so that thepick-up of the binder is 3%, and dried with hot air. The used PVA binder had a degree of polymerization of 700 and a degree of saponification of This nonwoven cloth was immersed in an aqueous 1.3% a-titanic acid solution having 0.5 titanium concentration and 1.3% hydrochloric acid concentration for one minute,

rinsed, and dried. The titanated nonwoven cloth was dipped in hot water at C. for 10 minutes but with no change in its configuration and in the steady form. After 5 min. immersion in hot water, the untitanated one disintegrated up to single fibers.

EXAMPLE 7 P VA fibers of 1.0 denier non-formalized, 5 mm. long havmg a dissolving temperature of 93 C. were used to manufacture a 100% PVA sheet with a Tappi paper machine. The sheet was pressed and dried at 105 C. for 10 minutes into the paper having a basic weight at 25 g./m. The paper was dipped in an aqueous 2.7% a-titanic acid solution having 1.0% titanium concentration and 2.7%

10 acid concentration was diluted with water, and 35% hydrochloric acid was added to it so that the solution was adjusted to a titanium concentration of 0.5% and a hydrochloric acid concentration of 1.3 to 10.0%. The solution was allowed to stand at room temperature. The rehydrochloric acid concentration for one minute, rinsed, sults are showninTable 1.

TABLE 1 Concentration ot- White precipitation Hydrochloric Specimen Titanium acid Number (percent) (percent) Iday 2days 4days Gdays '14 days 11-1.--- 0.5 1.3 r: a a: z z 0.5 2.2 o z a: z z 0.5 4.6 0 0 o z z 0.5 10.0 0 o o o o and dried. The titanated paper had its wet strength measured after the minutes immersion in hot water at 100 C. The breaking length was 1.5 km.

EXAMPLE 8 A web of PVA fibers, 3.0 denier, 50 mm. long, not formalized having a dissolving temperature in water of 93 C. was formed with a card and water-soluble 100% PVA fiber nonwoven cloth was prepared with a needle punch. The cloth weighed a basic weight of 25 g./m. The titanated nonwoven cloth was dipped one minute in an aqueous 2.7% a-titanic acid solution having 1.0% titanium concentration and 2.7% hydrochloric acid concentration, rinsed and dried. After 10 minutes immersion in hot water at 100 C., the cloth remained intact.

EXAMPLE 9 Ammonia water was placed in an aqueous hydrochloric acid solution of titanic acid, which was prepared by pouring tat-titanium tetrachloride into water to let a-titanic acid precipitate and filtered 0E, and the solid was taken out. The solid was dissolved in sulfuric acid and finally adjusted to 1.0% titanium concentration and 3.6% sulfuric acid concentration. The paper used in Example 1 was dipped in the above solution of u-titanic acid one minute, rinsed, and dried. The titanated paper was immersed in hot water at 100 C. for 10 minutes and had its wet strength measured. The longitudinal breaking length was In Table 1, x denotes the occurrence of precipitation, o no occurrence of precipitation and stable conditions, and 1 day, 2 days, etc. denote the number of days for which the specimens were allowed to stand after their preparation. When hydrochloric acid concentration was 1.3%, a precipitate occurred after one day, the insolubility effect being reduced. With hydrochloric acid concentrations of 2.2, 4.6, and 10.0%, the specimens were stable at least one day, 4 days and 14 days respectively. With concentrations of 2.2% and 4.6%, the insolubilization capability to PVA paper remained intact for one day, but with 10.0% concentration, the paper was degraded because of hydrochloric acid being too strong. I

EXAMPLE 12 Ammonia water was added to an aqueous hydrochloric acid solution of a-titam'c acid which had been prepared by pouring titanium tetrachloride into water to precipitate a-titanic acid and filtered off, and the solid was taken out, dissolved in sulfuric acid and finally made into an aqueous solution of a-titanic acid having 0.5 titanium concentration and 1.8 to 16.1% sulfuric acid concentration. It was allowed to stand at room temperature and as given in Table 2, with a sulfuric acid concentration of 1.8% allowed to stand one day, and precipitation occurred. With concentrations of 6.3% and 16.1% the solutions were stable more than 4 days and more than 14 days respectively.

3.0 km., and almost the same result as Example 1 was obtained. Hence it has been found that insolubilization capability with a mineral acid solution of a-titanic acid using sulfuric acid, etc. is good enough.

EXAMPLE 10 The nonwoven cloth in Example 3 was dipped one minute in an aqueous a-titanic acid solution having 1.0% titanium concentration and 3.6% sulfuric acid concentration prepared in Example 9, rinsed and dried. The titanated nonwoven cloth was dipped in hot water at 100 C. for 10 min., and the wet longitudinal breaking length was 1.1 km. The result similar to that of Example 3 was obtained.

EXAMPLE 11 An aqueous hydrochloric acid solution of u-titanic acid having 15% titanium concentration and 40% hydrochloric An aqueous solution (Specimen No. 13-1) of a-titanic acid having 15% titanium concentration and 40% hydrochloric acid concentration was diluted with water to make an aqueous solution of tat-titanium acid having a titanium concentration of 0.5% and a hydrochloric acid concentration of 1.3%. On the other hand, methyl alcohol and water were added to the aqueous solution of a-titanic acid prior to dilution, and made into an aqueous solution (Specimen No. 13-2) of a-titanic acid having a titanic concentration of 0.5 a hydrochloric acid concentration of 1.3%, and a methyl alcohol concentration of 5.0%. Both aqueous solutions were allowed to stand, and as given in Table 3 an aqueous solution of a-titanic acid containing 5% of methyl alcohol was stable more than 14 days. The control had white precipitation caused after a lapse of one day.

TABLE 3 White precipitation gpeeimen umber 1 day 4 days 6 days 14 days 13-1 Control treating solution z z :r a: 13-2 Treating solution in the o o o o invention.

EXAMPLE 14 a cylinder machine. The paper was dipped for one minute u m an aqueous solution of w-tltanlc acid having titamum and An q e sollltlon 0f acld h a tltalllum hydrochloric acid concentrations of 1.0 and 2.7% respecconcentratton of 15% and a hydrochloric acid concentrai l d i ll b k whil b i t k out b u e tion of 40% was diluted with water and made up into an of h weakness f the p Though titanation was dif. q e l o p S of a-tltamc acld 15 ficult to carry out, it became possible on treatingthe rayon having a titamum concentrtaion of 0.5% and a hydrochloric acid concentration of 1.3%. Previously, ethylene having concentrations f titanium, hydrochloric acid, and 8 Y f f lmnroured Into an Pndiluted u methyl alcohol of 1.0, 2.7 and 70% respectively. The ous solution of a-titanic acid and made up into an aqueous boiling f this titanated paper at did not cause solution of a-titanic acid (Specimen No. 14-2) having d f ti titanium, ethylene glycol, and hydrochloricacid concen- EXAMPLE 17 .trations of 0.5, 5.0, and 1.3% respectively. Both solutions .titanic acid and made up into an aqueous solution of awere allowed to stand and as given in Table 4, the control Paper having a basic weight of 10 'gJm. was prepared had white precipitation caused after a lapse of one day with a cylinder machine using as prime fibers 80 parts but the aqueous solution of a-titanic acid containing 5.0% rayon fibers of 1.5 denier and 5 mm. length produced by ethylene glycol was stable more than 14 days. the viscose process and as a binder. 20 parts PVA fibers,

' TABLE 4 White precipitation 8 imen umber 1 day 4 days 6 days 14 days 14-l...- Control treating solution a: z z x 14-2 Treating solution in the o o o o invention.

EXAMPLE 15 1.5 denier and 3 mm. long with a water-dissolving temperature of 60 C. The paper was treated with a hydrous al- An aqueous solutionof lit-titanic acid having titanium cohol solution of -titanic acid having titanium, hydroand hydrochloric acid concentrations of 15 and 40% rechloric acid, and ethylene glycol concentrations of 1.0, spectively was diluted with water and made up into an 2,7, d 60% respectively, and there was no irregularity paper with a hydrous alcohol solution of a-titanic acid aqueous solution of atitanic acid (Specim n N 40 in the treatment process by itself. The resultant titanated having titanium and hydrochloric acid concentrations of paper d d bofling'water at 100 C,-

0.5 and 1.3% respectively. Previously glycerin and water EXAMPLE 18 had been added to an undiluted aqueous solution of on- An aqueos solution of u-titanic acid having a' titanium titanic acid (Specimen No. 15-2) having titanium, hydroconcentration of 15%, a hydrochloric acid concentration chloric acid, and glycerin concentrations of 0.5, 1.3 and of 40% was diluted with water up to a titanium concen- 5.0% respectively. Both solutions were allowed to stand, tration of 3%. PVA having a polymerization degree of i and as given in Table 5, the control treating solution had 1500 and a degree of saponificationof 95.0% was disprepared by the. viscose process and 20 parts polyvinyl whiteprecipitation generated after a lapse of one day, solved in water and made up into a 3.0% aqueoussolubut the treating solution of a-titanic acid containing 5.0%

" glycerin was stable more than 14 days. of a-titanic acid having 1.0% titanium concentration,

" TABLE 5 i V White precipitation 8 imen umber 1 day 4 days 6 days p p 14 days .16-1 Control treating solution z a: a: 2:

15-2 Treating solution in the o o o o invention.

EXAMPLE 16 2.7% hydrochloric acid concentration and 0 to 2.0% PVA was finally prepared. It was allowed to sand. As given As prime fibers 80 parts rayon, 1.5-denier, 5 mm. long v in Table 6, an aqueous solution of u-titanic acid contain- -alcohol fibers, 1.5 denier, 3 mm. long having a dissolving 8 PVA Precipitated after y, b with a-PVA temperature in water of 60 C. were used for the manuconcentration of 0.2 to 2.0%, was stable more than 1'4 facture of paper having a basic weight of 10 g./m. with days.

TABLE 0 Concentration 01- Hydrochloric White precipitation Specimen PVA Titanium acid w Number (percent) (percent) (percent) 1 day 3 days 6 days 14 days 0 1. a7 1 z s x a 0.02 1.0 9.7 o o 0 o 0.25 1.0 2.7 o o o o 0.60 1.0 2.7 oo o o 1.00 1.0 2.7 o 0 0 o 2.00 1.0 2.7 o o o o tion. By mixing them little by little, an aqueous solution EXAMPLE 19 PVA having a polymerization degree of 650 and a saponification degree of 99.9% was dissolved in water and made up into a 3.0% aqueous solution. It was added to a aqueous solution of a-titanic acid and made up to an aqueous solution of titanium, hydrochloric acid and PVA concentrations of 1.0, 2.7, and 1.0% by adjusting the concentrations by a further addition of water. The aqueous PVA solution of u-titanic acid thus prepared was allowed to stand for 20 days, but no white precipitation was seen and it remained as colorless and transparent as the solution immediately after the preparation.

EXAMPLE 20 As in Example 19, an aqueous PVA solution of atitanic acid with concentrations of titanium, hydrochloric acid and, PVA of 1.0, 2.7 and 1.0% was prepared by use of PVA having a polymerization degree of 1800 and a saponification degree of 90% and allowed to stand 14 days with no resulting white precipitation. Then PVA containing paper having a water-dissolving temperature of 60 C. was treated with the solutions immediately after the preparation and 14 days after the preparation respectively. Both completely endured boiling water of 100 C. and could not be distinguished from each other.

EXAMPLE 21 Paper was manufactured with a cylinder machine using as prime fibers 80 parts 3.0-denier, 6-mm.-long nylon and as a binder 20 parts PVA fibers, 1.5-denier with a cut length of 3 mm., having a water-dissolving temperature of 75 C. The basic weight weighed 60 g./m. The resultant paper was dipped in an aqueous solution of a-titanic acid with a titanium concentration of 1.0% and a hydrochloric acid concentration of 2.7%, rinsed, and dried. After 10 min. immersion in boiling water at 100 C., Wet strength of the titanated paper was measured, and the longitudinal breaking length was 2.2 On the other hand, the untitanated paper completely distintegrated into single fibers on the immersion in boiling water at 100 C.

CONTROL EXAMPLE 22 An aqueous solution of a-titanic acid of a titanium concentration of and a hydrochloric acid concentration of 40% was diluted with water and made up into an aqueous solution of a-titanic acid with 1.0% titanium and 2.7% hydrochloric acid concentrations. The solution was equally divided into two parts. One was allowed to stand in the constant temperature bath at 45 C. and began to generate white precipitation after one hour, but the other was allowed to stand in a chamber at 25 C. and started to precipitate after hours.

EXAMPLE 23 Two types of aqueous solution u-titanic acid having 0.1% titanium concentration and 0.27% hydrochloric acid concentration on one hand and 0.2% titanium concentration and 0.54% hydrochloric acid concentration on the other hand were prepared. The PVA type paper in Example 1 was dipped one minute in each solution, washed, and dried. The titanated paper was steeped in 100 C. water and the one with 0.1% titanium concentration was insolnbilized but slightly swelled, and the other with 0.2% titanium concentration did not show any sweling with almost no change in its configuration.

EXAMPLE 24 Three types of aqueous u-titanic acid solutions having 0.5% titanium concentration and hydrochloric acid concentrations of 1.3, 4.6 and 10.0% respectively were 14 prepared. The PVA paper in Example 1 was dipped in the solutions one minute, washed, and dried.

These three kinds of paper titanated with the 3 kinds of solutions were placed in boiling water at C. 10 minutes and the following wet strengths were obtained.

Longitudinal break- Hydrochloric acid coning length, km.: centration, percent 2.4 I 1.3 2.2 4.6 1.5 10.0

With increase in the hydrochloric acid concentration, the paper strength lowered.

EXAMPLE 25 EXAMPLE 26 Titanium dioxide was placed in conc. sulfuric acid, heated, and made up into titanyl sulfate. It is dissolved in water up to a titanium concentration of 1%. The PVA type paper in Example 1 was dipped one minute in the solution, washed, and dried. The titanated paper was placed in boiling water at 100 C. for 10 minutes. The strength after the immersion was 0.3 km.

EXAMPLE 27 This example demonstrates the good fastness to washing of the paper according to the present invention. Water was placed up to the water level (40 liters) of the water tank in the washing machine, Hitachi Automatic Washing Machine SC-AT The temperature was maintained at 40:3 C. Detergents were added at 1 g. per liter, agitated, and well dissolved. Three pieces of specimens with load cloth attached were put into washing liquors so that the liquor ratio was 1:20.

The specimens were agitated for 10 to 15 minutes and dewatered while revolving the dewatering tank until the drain had almost disappeared. After draining, water was filled at normal temperature up to the water level, and agitated for 5 minutes. Washings were twice repeated. This step was repeated until the specimens were broken. The fastness to washing was evaluated by the number of washings whereby the specimens were broken. The PVA fiber paper in Example 1 was treated with a-titanic acid (treatments of Example 1), glyceryl titanate (treatments of Example 25), and titanyl sulfate (treatments of Example 26). The test results on fastness to washing are given in Table 7.

TABLE 7 Concentration Number titanium of Specimen number Types of treatments (percent) washings 1 tar-Titanic acid 1. 0 12 2. Titanyl sulfate 1. 0 6 3 Glyceryl titanate- 1. 0 4 4. Non-tr Put 1. 0 2

dissolves in water at 95 C. or below with an aqueous solution, prepared at 40 C. or below and containing e-titanic acid at a titanium concentration of 0.2 to 5.0% by weight and a mineral acid selected from the group consisting of hydrochloric acid in an amount of up to 14% by weight and sulfuric acid in an amount of 0.7% by weight or more, based on the weight of said aqueous solution; and thereafter rinsing and drying the impregnated paper or nonwoven fabric.

2. The process of claim 1 wherein said paper or nonwoven fabric contains a binder of water-soluble polyvinyl alcohol soluble in water at 90 C. or below in a form of fiber or resinous material.

3. The process of claim 1 wherein said aqueous solution contains 1 to 10% by weight of a lower aliphatic alcohol containing 1 to 4 hydroxyl groups.

4. The process of claimil wherein said aqueous solution contains 0.01 to 2% by weight of a polyvinyl alcohol derivative selected from the group consisting of polyvinyl alcohol, partially hydrolyzed polyvinyl ester, and partially acetalized polyvinyl alcohol.

5. The process of claim 1 wherein said aqueous solution is prepared by adding titanium tetrachloride to water at 40 C. or below; adding ammonia to the resulting solution; separating the generated precipitate from the solu- 1 6 tion; dissolving the precipitate in an aqueous solution of a mineral acid; and adding polyvinyl alcohol or a lower aliphatic alcohol thereto.

6. The process of claim 1 wherein the titanium concentration in said aqueous solution is 0.5 to 2.0% by weight.

7. The process of claim 1 wherein said aqueous solution contains sulfuric acid in an amount of 1.8 to 7.2% by weight.

References Cited UNITED STATES PATENTS 2,518,193 8/1950 Signaigo 260-913 VA 2,549,940 4/1951 Signaigo 26089.1 3,028,296 4/ 1962 Adams et a1. 162-146 3,318,856 5/1967 Deyrup 260-91.3VA 3,518,242 6/1970 Chrisp 260-913 VA S. LEON BASHORE, Primary Examiner F. FREI, Assistant Examiner US. Cl. X.R.

8-1155, DIG. 10; 162-146, 168, 182 l 

